Ok, I have just heard more rumor fodder concerning the "Walk-through" attraction(s). Weasley Wizard Wheezes isn't a "walk-through" per se. But it is being treated as one, or at least a unique attraction/retail venue. It is not a standard walk-through because there won't be a specific path to follow, but the shop will be filled with AAs, Special FX, Easter Eggs, and possibly a little pyro.
I am being told that the actual walk-through attraction is Borgin and Burkes.